Accessory drive and coupling



Jan. 9, 1951 F. w. EDWARDS ACCESSORY DRIVE AND COUPLING Filed July 24, 1944 INVENTOR. fiat/7K Ml ZJwar/s.

Patented Jan. 9, 195.1

.iA-QCESSORYD NDQQUEDIING' iwEramklini;

:QiEflmardSgj Detroit; Mich; assignor; to h Ght sle Gorpn on, fl hlandtaliarle; Mien-1e @QDFDQIQHP gofgllelmare 4 r invention relates -tovWindshidd-wipers;

More--particularly, it :rel-atesetm an improved meansfordriving --windshield--wipers: directly from the engine 'of wmotorwehiele; :bo'at," or thea like;

in use are well known; Those actua-t'eds by intake manifold vacuum vary in:: speed: withithe: thro.t.. tie opening and 1v load" anti -frequently stop:when

they are needed most. Those-drive-Inlayelectrical;

motors are noisy and cause severe drainconfthe battery.

various -attemptehave-ibeenz-madeto:driveethewiper arms. ,directlyi-from; the .enginekthrough Accordin ly. it:isfvherprime,stobiflcteroifmwinvene tien;toproyidean:improved drivezmean. for he windshield Wiper' bladeszthat; QYHZ mES: and. ayoids theaforesaiddiifieuities;

of engine speed.

; Still-:another:ebflwtaisr qrplffiy de,1.11;..th6r-WE drive;- mechanism means;rfomabsqllbin shacks; 301-31, contactscorrespon slip rin s she; n

The deficienciesfwindshieldwipen drivestnowi I ,1;,25 by-a1shaftJSswhich iedrivenvfrom theaoil p .Anothemobiect; isle-tom V flfl'; a; wipexrzrdriyi V v that;issubstantiallyzconstrarrit lllLSQBfiQ" re endle sz causedebx suddenech nges: :inz-l'ewimm the; w per;-

entsfrom. the, {allowi g speoificetienp wherein; I;

have; described preferred;embodimentsior my vention.

In-thee drawings; which;.accom1any :theesn eir ficatiqn,

Fig. 1151s a diaerammaticiviemofithe-zcem le r wiper system, certainapartsrbeing,. showneinwsecmeehwiiih. wworm wheelgifiamqunted i1; the casl-l" 2 posed centrally of the w windshieldf-ra-me; r'I'he cra-nle lli is-rotated by a fiexible drive cable I8; of standard ty-pe. The meeha-nism just described is more or less conventionalandhasnot been shown -irr-detail; it -being understoodthat: rotation of the innerelement-l9 of cable t liiawill ro-.. tats crank; l 6" and this .-rotarymotion, through; theintermediary of the linksu! 5. and cranks-v; M', will be" translated into osci11at0ry)motioneon' the arms I l.

'--In the presentinstance, the; wipersare; driven; directly-from the -l-regu1ar-engine oil.- pump 21): through aneddy-current: coupling 52''. :This is; for 'eonyenience; -i it being 1 under-stood that z-the v eddy-current coupling could as-well-ibe mounted on and/01 .drivenvby the'generator, fuel: pump;

f an; or. other accessory.

1:20; shaft-122gthe speed?thereofsvarying-in accordance with the speed-of:- the engine.

- 'Ilhe eddy-.current; coupling-censists essentially, of a casing 23 in whichais rotatablynmounted a',--driving "member :2 4; The: member; :2 4 is.v carried 29 3,1311 thespe'ed thereof; 'The member :2.4;c a n asfield' coil 2 {is-which i s;energizedz flqm-thegtfigu lar; vehieleqbattery. 2'1 through. a; switch 2 2} and; arr-variable resistanceyZQ. A, paiizgof bru$hfisi torenergi zez-the. coil and still-permitirotatiom oinmem-ber 2-4 The-.. 1a f0iier.= is; "provided; with ripheral-teeth, 3 2';

Surrounding the driving member 24 iSg-bhe ggd riven; memberzzoilthe couplin SQ-Whifih 15351113- porteckfor. rotationrelative; to themember {A and- Midis; Jmmembers-M the casing- 2 3.1 by: a bearing #3 4:; and a. bushingfi 5, A sha-ftwiifi'ifermedintegral-1 with the member. 3 h-aseworm" teeth: :31" cut iHlIif/Se outer. epd wh' h:

inerportion The worm. wheel;v is; directly connected to'the. inner drivin e men of; the .Qa l

When.;the:-.-freld coil: 25,1. en rgize and the:

v 7 m emz l rotated,,maens efiuaw l srrmund t hefififl'iaind will travel .422 thee neephetween membersdl anct33; where it-wiil prpduce -regiohs f: a ternatin highlands low; .fi e enityri t the memberflfix causing eddyr currents to flow theree in. A: magnetie effect; is. thuszplroduqed which causes; the driven member .3 3; to. followi-thet driw ineamemherzu Rand t9; try and; catchupiwith; it; ere 'th of such devices and this slip may be varied in accordance with the excitation of the field. The drive member 24 is preferably driven at all times that the engine is operating and the wipers may be started by swinging the arm 40 to energize the coil 26.

The switch 28 is preferably the ignition switch of the engine and when it is closed and the engine is running, swinging of the arm 40 clockwise will energize the field coil 26. The speed of the wiper blades l2 may be varied by the driver to suit different weather conditions, but. once the arm 40 is set in a selected position, the speed of the coupling driven member 33 (and that of the blades l2) will remain substantially constant regardless of engine speed. This is due to the inherent characteristic of the eddy current coupling which may be designed to provide desired speed characteristics.

In installations where extremely good speed regulation is desired and/or where the engine speed varies between wide limits, some form of automatically operable speed governing device on the coupling is desirable.

Fig. 2 shows an eddy-current coupling which may be substituted bodily for the coupling 2| in the Fig. l apparatus. The Fig. 2 coupling comprises a driving member 4| having a drive shaft 42. The member 4| carriesa" field coil 43and is driven from the oil pump as is the case in Fig. 1. A casing 44 boltedtoithe 'pump casing encloses the coupling mechanism and'supports the end of the flexible cable l8. The coil 43 is supplied with current through slip rings 45 and brushes 46. The driven member 41 of the coupling is supported by a ball bearing 48 which may be of the double row type or of theneedle type if required for greater stability. The inner race of the bearing is carried by a bushing 49 which is internally splined and which slides on splines 5|] of shaft 42. The bearing outer race supports the hub portion 5| of the driven member 41 and is fixed thereto.

Pivotally mounted on the portion 5| are a plurality of levers 52 having weights 53 on their outer ends. The inner ends of the levers 52 are provided with bearing surfaces 54 which bear on one surface of a collar 55 carried by shaft 42. The driving connection between the cable I8 and member 41 comprises a cage 56 which carries a conical part 51 having a cylindrical squared (or splined) portion 58 which has a sliding connection with the end lug 59 of the cable.

When the coil 43 is energized, flux travels around the coil and passes through the teeth 60 across the air gap and through that part of the member 41 which radially overlies the teeth. When driving member 4| is rotated, regions of alternate high and low density flux are produced in member 41 and the latter tends to follow the member 4! through magnetic attraction.

The Fig. 2 coupling is preferably designed to have a predetermined slip curve at constant load as the speed of the driving means varies; A decrease in output torque tends to reduce the slip between the members 4i and 41 and results in an increase in the speed of 41. Any increase in the speed of 41 causes the weights 53 to move radially outwardly because of the increased centrifugal force and such action reacts through the path area, or in other words, lengthens the air gap between the teeth 60 and the inner surface of member 41, which results in increased slip between the members. Magnetic action across the teeth will restore the members to radially aligned position when centrifugal force on weights 53 is decreased.

During operation of the coupling at varying engine speeds, the centrifugal force on weights 53 will maintain the weights in such positions that the speed of the driven coupling member 41 will remain constant.

An important feature of my improved wiper drive resides in the shock absorbing characteristics of the eddy-current coupling, which will slip -under sudden increased load and relieve the cable and gears of shock which might cause breakage. v

Thus it may be seen that I have provided an improved windshield wiper mechanism characterized by an improved driving means which is positive and steady under all conditions of operation, is economical of electric current, shockproof and simple in construction.

The embodiments shown and described for illustrative purposes may be changed and rearranged by those skilled in the art to suit different conditions, it being understood that my invention is intended to be limited only as set forth in the claims appended below.

I claim:

1. An eddy-current coupling for providing a constant speed output when connected to a variable speed input, comprising, an input member having a mounting shaft; a field coil in said in-- put member; a splined extension on said shaft; a bushing slidable on said splined extension; an

anti -friction bearing carried by said bushing; an output member carried by said bearing and having a portion extending in surrounding relation with the input member; a plurality of weighted levers pivotally mounted on said output member, said levers bearing at their radial inner ends on an axially fixed portion of the assembly whereby increase in speed of saidoutput member above a predetermined speed will cause said levers to move said output member axially on said splined extension.

2. An eddy-current coupling for providing a constant speed output when connected to a variable speed input,'comprising an input member, a bushing mounted on said input member for slidable movement relative thereto, an anti-friction bearing carried by said bushing, an output member carried by said bearing and having a por-' able speed input, comprising a driving member;

a driven member, a bushing mounted on a first one of said members for slidable movement relative thereto, an anti-friction bearing carried by said bushing, the second of said members being carried by said bearing and having a portion ex tending-in surrounding relation with said first membrffa field coil on one of said :members, a plurality'of weighted levers pivotally mounted on mamas said second member, said levers bearing at their radial inner ends on an axially fixed portion of the coupling whereby increase in speed of said second member above a predetermined speed will cause said levers to slide said second member axi- ,5 ally relative to said first member.

FRANKLIN W. EDWARDS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date LOGklin Sept. 15, 1925 15 Number Number 

